The only way to check if soil is acidic or alkaline is to run a soil test to check the pH. The test results will tell you if the soil is acidic or not. I think you also asked about hollies. Hollies do best where the soil pH is nearly neutral or mildly acidic to somewhat more acidic, or from about 5.25 to 6.75 -- this is a fairly broad range.

Your local county extension should be able to help you with the testing and interpreting the results with an eye on growing hollies. In many cases using an acidic mulch such as pine bark combined with a slow release fertilizer such as Hollytone is adequate to keep them happy, but you would need to run the tests to be sure. They may also be able to diagnose more specifically what is affecting the hollies. I hope this helps!